Mixing supply tank



H. J- M VEY ETAL MIXING SUPPLY TANK Filed Feb.

March 15, 1966 United States Patent 3,240,476 MIXING SUPPLY TANK Harold J. McVey, Walled Lake, Norman A. Baker, Grosse Pointe Farms, and Orvin A. Eggen, Detroit, Mich., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., a corporation of New York Filed Feb. 6, 1963, Ser. No. 256,606 4 Claims. (Cl. 259-44) The present invention broadly relates to mixing apparatus and more particularly to an improved combination storage supply tank and mixing apparatus for supplying uniformly blended liquids on a continuous or a periodic makeup basis.

The mixing and supply apparatus comprising the present invention is particularly suitable for forming uniform slurries, suspensions, emulsions, as well as Solutions of materials difiicult to dissolve and for maintaining such liquids in a substantially homogeneous condition enabling a continuous or periodic withdrawal thereof from the apparatus as may be required by the associated apparatus or process supplied thereby. The present apparatus is especially applicable for supplying makeup liquids for replenishing various treating and cleaning solutions wherein such solutions must be maintained within a relatively narrow range of concentration.

The increased emphasis on automation and control of such treating solutions has increased the criticality of providing replenishing liquids which are of a known and uniform concentration whereby controlled automatic additions thereof maintain the treating solution within the prescribed range of concentration. Heretofore, relatively large fluctuations in the uniformity of such makeup liquids added to a treating solution either on a continuous controlled volumetric rate or on a periodic or intermittent volumetric rate has occasioned erratic fluctuations in the resultant concentration of the replenished treating solution frequently impairing its treating efficiency.

It is accordingly a principal object of the present invention to provide an improved mixing supply apparatus which effects continuous recirculation and agitation of a liquid slurry, suspension, emulsion, etc., preventing segregation and Stratification thereof assuring a continuous supply of a substantially uniform and homogeneous mixture thereof.

Another object of the present invention is to provide an improved mixing supply apparatus which is extremely eiiicient in effecting rapid solution of soluble materials and maintaining the resultant solution in a homogeneous condition preventing stratification or precipitation of the dissolved constituents therefrom.

Still another object of the present invention is to provide an improved mixing supply apparatus which is of simple design, of efficient, durable and maintenance free operation; and of economical manufacture and use.

The foregoing and other objects and advantages of the present invention are achieved by providing a tank preferably formed with at least a portion of the side walls thereof inwardly tapered providing a base of decreased area and in which a tube extends downwardly to a point spaced from the base incorporating an axially extending rotatably journaled shaft therein. The lower end of the shaft projects beyond the end of the tube and is provided with an agitator thereon disposed contiguous to the base of the tank. The annular region formed between the periphery of the shaft and the inner surface of the tube provides a conduit for an upwardly rising turbulent flow of liquid created in response to impellers mounted on the shaft within the tube which are rotated at high speed. The liquid is withdrawn from the tube at the upper end portion thereof spaced above the level of the liquid in the tank and is discharged into a suitable conduit or trough formed with a drainage line through which a selected quantity of the blended liquid is withdrawn to a point exteriorly of the tank while the remaining liquid is recycled back into the tank for recirculation.

Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a plan view of a mixing supply tank constructed in accordance with the preferred embodiments of the present invention;

FIG. 2 is a side elevational view partly in section of the mixing tank shown in FIGURE 1, and

FIG. 3 is a front elevational view partly in section of the mixing supply tank shown in FIGURE 1 and illustrating in particular the tube and axial impellers for effecting recirculation of the liquid in the tank.

Referring now in detail to the drawings, the mixing supply apparatus as illustrated comprises a tapered receptacle or tank indicated at 10 comprising a pair of upright substantially planar side walls 12 and a pair of side walls 14 which are angularly inclined inwardly along the lower portion thereof imparting a taper to the lower portion of the tank 10. The straight side walls 12 and angular side walls 14 terminate and are connected to a base 16 which is of an area substantially less than the cross sectional area of the upper portion of the tank. A suitable drain conduit 17 including a valve 19 is provided adjacent to the base of the tank as shown in FIG. 3 for draining any residuary solution therefrom as may be required from time to time and during a cleaning of the interior of the tank. The corners of the tank are reinforced by vertically extending angle iron members 18 which also serve as legs for supporting the tank in an upright position. An angle iron reinforcing flange 20 is rigidly aflixed to and extends around the upper edge portion of the tank 10 as is best seen in FIGURE 1. The upper portion of the tank 10 is closed by a coverplate 22 which is formed with a hingedly mounted door 24 as shown in phantom in FIGURES 1 and 3 for gaining access to the interior of the tank for loading materials therein.

A pump and mixer assembly generally indicated at 26 is mounted on the coverplate 22 and includes an L-shaped frame 28 reinforced by triangular members 30 on which a suitable motor 32 is mounted. The base 34 of the L- shaped frame 28 is adapted to be securely fastened to the coverplate 22 such as by means of bolts, for example.

The coverplate 22 underlying the base 34 of the L- shaped frame 28 is provided with a bore therethrough through which a cylindrical tube 36 extends having the upper end thereof rigidly aflixed to the underside of the base 34. The lower end of the tube 36 extends downwardly into the interior of the tank to a point spaced from the base 16 thereof. A shaft 38 extends axially through the tube 36 and is rotatably journaled at the lower end portion thereof by means of a bearing 40 supported by webs 42 affixed to the inner peripheral surface of the tube 36. The upper end portion of the shaft 38 extends through a bore 44 in the base 34 and is rotatably journaled in a bearing 46 connected to the upstanding portion of the L-shaped frame 23. The upper end of the shaft 38 is connected by a suitable coupling 48 to the output shaft 50 of the motor 32.

The lower end of the shaft 38 projects beyond the lower end of the tube 36 and to which is affixed an agitator 52 which is disposed contiguous to the base 16 of the tank. The agitator 52 is preferably of a propeller design comprising a plurality of blades angularly disposed relative to a plane perpendicular to the axis of rotation of the shaft and oriented so that upon rotation of the 3 shaft the liquid is propelled by the agitator upwardly toward the inlet end of the tube 35. The turbulance created by the agitator is effective to entrain any solid particles which may have deposited on the base of the tank. Alternatively, the angularity of the agitator blades can be oriented so that the liquid is propelled downwardly against the base effecting a high velocity impingement thereagainst and a washing an upward carrying of any solid deposits which may have accumulated thereon.

The periphery of the shaft 38 extending through the tube 36 defines an annular region through which an upward flow of liquid is directed 'by means of a plurality of impellers 54 affixed to the shaft and disposed within the annular region. The impellers 54 are comprised of a plurality of blades angularly disposed relative to a plane perpendicular to the axis of rotation of the shaft and are oriented whereby the blades in response to rotation thereof, are effective to pump the liquid upwardly through the annular column. The specific angularity of the blades on the impellers 54 and on the agitator '52 can be varied depending on the speed of rotation of the shaft and the vertical distance between the level of the liquid in the tank and an outlet port 56 disposed in the upper end portion of the tube 3-6 which is disposed above the level of the liquid therein. A further consideration relates to the desired flow rate to achieve the requisite speed of turnover of the liquid in the tank to maintain a substantially homogeneous mixture of the slurry, suspension, or emulsion, as well as in providing the requisite speed and efiiciency in effecting the dissolving of soluble materials in solution.

Conventionally, blade angles disposed at an angularity ranging from about 15 up to about 30 from the plane of rotation and rotating at a speed of from between about 1000 rpm. up to about 2000 rpm. provide a satisfactory flow rate providing for a complete turnover of the liquid within the tank ranging every one to five minutes. The pumping capacity of the impellers 54 is maximum when the tank is filled with liquid to a level slightly below the outlet port 56. As liquid is withdrawn from the tank for replenishment of a main treating tank solution, the volumetric flow rate decreases. However, since the volume of liquid in the tank is less, the net turnover rate remains substantially constant. The pumping of the liquid upwardly continues until the level of the liquid drops to a point adjacent to the lower end of the tube 36 at which point air is drawn into the tube causing cavitation and preventing further pumping. At that point, due to the tapered configuration of the tank, approximately 85% to 90% of the liquid has been withdrawn. The tank thereafter is recharged with a new batch of liquid which is mixed and pumped therethrough in a manner as hereinbefore described.

In either event, a plurality of impellers 54 are employed, which are disposed in longitudinally spaced increments along the shaft 38 within the annular column. In the exemplary arrangement shown in the drawings, three impellers 54 are employed. It will be appreciated, however, that satisfactory operation has also been achieved by employing two impellers or more than three impellers consistent with a specific mixing installation. The tips of the blades of the impellers 54 are disposed in close clearance relationship relative to the inner surface of the tube 36 to provide increased efficiency in their pumping action.

In accordance with the exemplary construction shown, the pump and mixer assembly 26 is effective to agitate the liquid adjacent to the base of the tank preventing the accumulation of any sediment thereon and to simultaneously withdraw liquid from the lower stratum of the tank and pump it upwardly to be discharged through the outlet port 56. The liquid from the outlet port 56 is discharged into a conduit or trough 53 which is disposed adjacent to the upper edge of the tank and extends along two of the side walls thereof. The trough 58 adjacent to the outlet port 56 is formed with a drain conduit 60 for withdrawing either continuously or on a periodic basis the agitated uniformly mixed liquid to be supplied to a point exteriorly of the tank. When the mixing supply apparatus is employed in combination with an automatic treating solution replenishing system, the drain conduit 60 can be provided with a suitable remotely actuable valve 62 such as a solenoid valve, having a solenoid 62A, which is opened periodically to effect replenishment of a treating solution disposed remotely from the apparatus. Exemplary of such automatically activated valve systems which may be used is that shown in US. Patent 2,732,069, issued January 24, 1956.

Alternatively, the valve 62 may comprise a suitable flow control valve for discharging a continuous stream of the liquid in the tank at a variable controlled volume to a suitable apparatus associated therewith.

In order to maintain an appropriate level of the liquid in the trough adjacent to the drain conduit 60, a suitable darn or weir 64 is provided having a height sufficient to maintain the drain conduit beneath the level of liquid in the trough. The drain conduit 60 is located above the base of the trough so as to avoid the withdrawal of any sedimentary or precipitated solids which may have settled to the base of the trough assuring that only a uniform homogeneously mixed liquid is discharged through the drain conduit. The bottom of the dam 64 adjacent to the base of the trough is provided with one or a plurality of bleed apertures 65 therethrough to continuously withdraw liquid and any precipitated solids from the base of the trough as well as providing for drainage of that section of the trough when the apparatus is shut down. The re maining or surplus liquid discharged from the outlet port 56 into the trough 58 drains along the downwardly inclined trough and spills over the dam '64 and passes therefrom down the remaining trough section and is discharged through a port 66 back into the upper portion of the tank. The point of discharge or return of the recirculated liquid is disposed remotely from the inlet of the pump and mixer assembly effecting thereby a continuous uniform turnover of the liquid within the tank.

In accordance with the preferred construction of the apparatus comprising the present invention, a plurality of radially projecting and longitudinally extending guide vanes 68 are preferably afiixed to the inner surface of the tube 36 above the uppermost impeller 54 therein to reduce the swirl of the liquid passing upwardly through the annular column providing a more unidirectional flow at its point of discharge through the outlet port 56. The helical flow pattern or swirl of the liquid passing upwardly through the lower portion of the annular column serves the dual function of creating a turbulance which breaks down any agglomeration which may have occurred of the suspended particles in the liquid or alternatively, effects an increase in the rate of solution of a soluble material being blended and dissolved in the liquid. To avoid any leakage of the upwardly rising column of liquid through the bore 44 in the base 34 of the frame, a suitable low friction plastic seal indicated at 70 in FIGURE 3 is preferably provided in combination with a slinger ring or disc mounted on the shaft 38.

In accordance with the construction of the apparatus as herein-before described and as shown in the drawings, substantially homogeneous slurries, suspensions, emulsions, etc. have been created and maintained assuring a uniform supply through the drain conduit 60 to the process apparatus or replenished treating solutions associated therewith. In addition, relatively rapid and uniform solution of dry particulated materials in a solvent has been achieved by simply adding the dry particulated material to the solvent in the tank achieving substantially complete dissolution thereof. conventionally, during the initiation of a mixing and supply cycle, the tank is charged with the liquid which may either contain the suspended solids therein or alternatively to which the solids to be suspended or dissolved are subsequently added. The motor 32 is energized effecting continuous recirculation of the liquid upwardly through the tube 36 which is returned to the tank through the port 66 in the trough 58. As the level of the liquid in the tank decreases, as occasioned by the continuous or periodic withdrawal of the liquid through the drain conduit 60, the level approaches the lower end of the tube 36. When the level reaches a point corresponding to the inlet end of the tube 36, air is withdrawn into the tube effecting cavitation of the pump and halting its pumping characteristics. It will be appreciated that by virtue of the angularly inclined side walls 14, the net volume remaining in the tank when the li uid level drops below the lower end of the tube, comprises a relatively small percentage such as from about to about of the total liquid initially present. The angularly slanting side walls 14 also serve to directionally guide any solid precipitates downwardly toward the agitator 52 from which they are driven upwardly and are drawn into the inlet of the tube.

While it will be apparent that the preferred embodiments herein illustrated are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A mixing supply apparatus comprising a tank for storing a liquid therein, a tube extending downwardly into said tank having the lower end thereof disposed in spaced relationship from the base of said tank, a shaft extending axially through and rotatably journaled in said tube and defining an annular column between the periphcry of said shaft and the inner surface of said tube, said shaft projecting downwardly beyond said lower end of said tube and formed with an agitator thereon disposed contiguous to said base of said tank, a plurality of impellers on said shaft disposed within said annular column, said tube formed with an outlet port in the upper end portion thereof, means for rotating said shaft and said impellers thereon for effecting an upward axial flow of liquid through said annular column for discharge through said outlet port at a point above the level of liquid in said tank, a conduit disposed adjacent to the upper edge of said .tank for receiving the liquid discharged from said outlet port, said conduit formed with first drainage means for draining therefrom to a point disposed exteriorly of said tank and second drainage means for recirculating the remaining liquid therein back into said tank, said first drainage means including means selectively operable for effecting :periodic withdrawal of liquid from said conduit.

2. A mixing supply apparatus comprising a tank for storing a liquid therein and having at least a portion of the side walls thereof inwardly tapered toward a base of a reduced area, a tube extending downwardly into said tank having the lower end thereof disposed in spaced relationship from the base of said tank, a shaft extending axially through and rotatably journaled in said tube and defining an annular column between the periphery of said shaft and the inner surface of said tube, said shaft projecting downwardly beyond said lower end of said tube and formed with an agitator thereon disposed contiguous to said base of said tank, a plurality of impellers on said shaft disposed within said annular column, said tube formed with an outlet port in the upper end portion thereof, means for rotating said shaft and said impellers thereon for effecting an upward axial flow of liquid through said annular column for discharge through said outlet port at a point above the level of liquid in said tauk, a conduit disposed adjacent to the upper edge of said tank for receiving the liquid discharged from said outlet port, said conduit formed with first drainage means for draining liquid therefrom to a point disposed exteriorly of said tank and second drainage means for rcoircu lating the remaining liquid therein back into said tank, said first drainage means including means selectively operable for effecting periodic withdrawal of liquid from said conduit.

3. A mixing supply apparatus comprising a tank for storing a liquid therein and having at least a portion of the side walls thereof inwardly tapered toward a base of a reduced area, a tube extending downwardly into said tank having the lower end thereof disposed in spaced relationship from the base of said tank, a shaft extending axially through and rotatably journaled in said tube and defining an annular column between the periphery of said shaft and the inner surface of said tube, said shaft projecting downwardly beyond said lower end of said tube and formed with an agitator thereon disposed contiguous to said base of said tank, a plurality of impellers on said shaft disposed within said annular column, guide means disposed in said annular column for guiding the flow of liquid therethrough, said tube formed with an outlet port in the upper end portion thereof, means for rotating said shaft and said impellers thereon for effecting an upward axial flow of liquid through said annular column for discharge through said outlet port at a :point above the level of liquid in said tank, a conduit disposed adjacent to the upper edge of said tank for receiving the liquid discharge from said outlet port, said conduit formed with first drainage means adjacent to said outlet port for selectively draining liquid therefrom to a point disposed exteriorly of said tank and second drainage means for recirculating the remaining liquid therein back into said tank, said first drainage means including means selectively operable for effecting periodic withdrawal .of liquid from said conduit.

4. A mixing supply apparatus comprising a tank for storing a liquid therein and having at least a portion of the side walls thereof inwardly tapered toward a base of a reduced area, a tube extending downwardly into said tank having the lower end thereof disposed in spaced relationship from the base of said tank, a shaft extending axially through and rotatably journaled in said tube and defining an annular column between the periphery of said shaft and the inner surface of said tube, said shaft projecting downwardly beyond said lower end of said tube and formed with an agitator thereon disposed contiguous to said base of said tank, a plurality of impellers on said shaft disposed within said annular column, said tube formed with an outlet port in the upper end portion thereof, means for rotating said shaft and said impellers thereon for effecting an upward axial flow of liquid through said annular column for discharge through said outlet port at a point above the level of liquid in said tank, a trough disposed adjacent to the upper edge of said tank and extending along at least one side thereof for receiving the liquid discharged from said outlet port, said trough formed with first drainage means for selectively draining liquid therefrom to a point disposed exteriorly of said tank and second drainage means for recirculating the remaining liquid therein back into said tank, and dam means in said trough for maintaining a prescribed minimum level of liquid in said trough adjacent to said first drainage means.

References Cited by the Examiner UNITED STATES PATENTS 1,982,002 11/1934 Hatch 259-97 X 2,008,684 7/ 1935 Craddock 25997 2,096,728 10/ 1937 Bighouse.

2,111,726 3/1938 Plews.

2,346,366 4/ 1944 Durdin 259-97 2,657,912 11/1953 Liebman 259107 IRVING BUNEVICH, Primary Examiner.

WALTER A. SCHEEL, Examiner. 

1. A MIXING SUPPLY APPARATUS COMPRISING A TANK FOR STORING A LIQUID THEREIN, A TUBE EXTENDING DOWNWARDLY INTO SAID TANK HAVING THE LOWER END THEREOF DISPOSED IN SPACED RELATIONSHIP FROM THE BASE OF SAID TANK, A SHAFT EXTENDING AXIALLY THROUGH ANS ROTATABLY JOURNALED IN SAID TUBE AND DEFINING AN ANNULAR COLUMN BETWEEN THE PERIPHERY OF SAID SHAFT AND THE INNER SURFACE OF SAID TUBE, SAID SHAFT PROJECTING DOWNWARDLY BEYOND SAID LOWER END OF SAID TUBE AND FORMED WITH AN AGITATOR THEREON DISPOSED CONTIGUOUS TO SAID BASE OF SAID TANK, A PLURALITY OF IMPELLERS ON SAID SHAFT DISPOSED WITHIN SAID ANNULAR COLUMN, SAID TUBE FORMED WITHIN AN OUTLET PORT IN THE UPPER END PORTION THEREOF, MEANS FOR ROTATING SAID SHAFT AND SAID IMPELLERS THEREON FOR EFFECTING AN UPWARD AXIAL FLOW OF LIQUID THROUGH SAID ANNULAR COLUMN FOR DISCHARGE THROUGH SAID OUTLET PORT AT A POINT ABOVE THE LEVEL OF LIQUID IN SAID TANK, A CONDUIT DISPOSED ADJACENT TO THE UPPER EDGE OF SAID TANK FOR RECEIVING THE LIQUID DISCHARGED FROM SAID OUTLET PORT, SAID CONDUIT FORMED WITH FIRST DRAINAGE MEANS FOR DRAINING THEREFROM TO A POINT DISPOSED EXTERIORLY OF SAID TANK AND SECOND DRAINAGE MEANS FOR RECIRCULATING THE REMAINING LIQUID THEREIN BACK INTO SAID TANK, SAID FIRST DRAINAGE MEANS INCLUDING MEANS SELECTIVELY OPERABLE FOR EFFECTING PERIODIC WITHDRAWAL OF LIQUID FROM SAID CONDUIT. 